The present invention relates to apparatus for forming material, such as metal, and particularly relates to a safety control system for a metal bending or forming machine having a relatively movable die and head for forming metal therebetween wherein the safety control system is operable to disable the machine in the event an obstruction, other than the metal being formed, is located between the die and head.
Many different types of material forming machines, e.g., metal bending or forming machines, have been proposed and constructed in the past. Generally, these machines have the capability to perform various metal bending operations, such as forming and hemming. One such metal bending or forming machine, which is the subject of U.S. Pat. No. 2,456,749, has an elongated, generally cylindrical, lower die rotatably carried by a frame. The die has a plurality of elongated bending or forming grooves spaced one from the other about its periphery. Disposed above the lower die and movable vertically on the frame toward and away from the die is a head. The head carries an upper die or forming member along its lower edge in spaced relation to the lower rotatable die.
In use, the lower die is indexed into a rotary position with a selected one of its grooves in confronting spaced relation to the upper die or forming member. Upon disposition of material, e.g., metal, between the upper and lower dies, hydraulic cylinders are actuated to move the head, and consequently the upper die, toward the lower die to accomplish the selected forming operation on the metal between the dies. Once the material is formed, the hydraulic pressure is relieved and return springs displace the upper head and forming member away from the lower rotatable die to return the head to its initial or rest position.
While machines of this type have proved remarkably well suited for accomplishing various forming operations, the material to be formed is usually manually located in the gap between the upper and lower dies by the machine operator. This exposes the machine operator to serious injury. For example, when locating the metal in the machine, the operator may obstruct the machine by locating one or both of his arms or hands, or his finers between the upper and lower dies. If the machine is inadvertently actuated at that time, injury to the machine operator including loss of one or more hands, arms, or fingers may result. Other types of obstructions may also be inadvertently located between the upper and lower dies during forming operations. For example, tools or jigs may accidentally be located in the gap between the dies. Actuation of the machine under those circumstances could damage either or both of the upper and lower dies and possibly also injure the machine operator. Consequently, there is a demonstrable need, in material forming apparatus of this type, for a safety control system operable to disable the machine or render it inoperable in the event an obstruction, other than the material to be formed, is located between the working members of the machine.